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## QuestionPhysicsClass 12

Is it necessary for a transmitting antenna to be at the same height asthat of the receiving antanna for line of sight communication? A TV transmitting antenna is 81 m tall. How much service area can it cover, if the receiving antena is at the ground level?

In LOS communication, it is not necessary that transmitting antenna and receiving antenna are at same height. Only requirement is that there must not be any obsacle in between.
Given, $${h}={81}{m}$$
$$\therefore$$ Distance upto which transmission can be made
$$={d}=\sqrt{{{2}{R}{h}}}$$
$$=\pi{d}^{{2}}$$
$$={2}\pi{R}{h}$$
$$={2}\times\pi\times{6.4}\times{10}^{{6}}\times{81}{\left({m}^{{2}}\right)}$$
$$={3258}{k}{m}^{{2}}$$.
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